In order to evaluate performance of a control system of an automobile engine, there is proposed a device which is configured to combine a control model having a control algorithm to be implemented in the control system and an engine model modeling an actual engine in a predetermined method, import a physical quantity (e.g., amount of intake air) having an effect on an operating condition set in the engine model to the control model from the engine model while imaginarily making the engine model operate in a predetermined input condition, calculate a manipulated variable of a controlled equipment, such as a fuel injection valve based on the imported physical quantity, provide the manipulated variable to the engine model to confirm control efficiency of the control algorithm (e.g., see Japanese Patent Application Laid-Open (JP-A) No. 4-159439). Additionally, there exists JP-A Nos. 2003-108697 and 7-28505 as prior art documents related to the present invention.
The above conventional device simply changes input conditions of the engine model and confirm its control efficiency. However, in the case of actual vehicles, manufacturing tolerances exist in controlled equipments. Accordingly, the actual manipulated variable differs from the instructed value of manipulated variable and, with those differences, the operating state of the engine may be changed. Further, regarding various physical quantities such as amount of intake air or purification rate of an exhaust purification catalyst which are considered by the engine model, variation occurs in the actual engine in accordance with manufacturing tolerance, or differences in various parameters such as atmosphere temperature, fuel physical characteristics of engine components or the like, which detect or determines the physical quantities. According to the conventional devices, prediction of control efficiency in consideration of the above described differences in manipulated variables or variations in physical quantities cannot be provided. Therefore, in order to evaluate the control system accurately, it is required to control the actual engine with the control system to confirm the control efficiency. As a result, there have been problems such that evaluating the control system takes a lot of efforts, or that development period is protracted.